Patent Literature (PTL) 1 relates to a scheme with which, if a plurality of files of the same content are stored in a storage resource, the files are consolidated into a single file and then managed. According to PTL 1, one of multiple volumes storing therein duplicating files is selected as a destination volume of the consolidation on the basis of loads on the multiple volumes in order to avoid the concentration of loads on a highly loaded volume as a result of data de-duplication.
PTL 2 describes how to achieve easy migration of data and snapshot configurations from a first storage control apparatus to a second storage control apparatus. Specifically, the storage content of the oldest generation first snapshot volume is firstly restored in the second volume. Then, in order from the oldest generation to the newest generation, differential data is detected between the content of the first snapshot volume of a migration-target generation and that of the first snapshot volume that is one generation newer than the first snapshot volume of the migration-target generation. Then, the detected differential data is transferred to the second storage control apparatus and written into the second volume.
PTL 3 describes how to achieve continuous provision of snapshots to a client when migration of data is performed on a file basis between server apparatuses. When data is transferred from a migration-source server to a migration-destination server via an intermediate server, data in a differential volume is transferred simultaneously. Then, the migration-destination server reconstructs data in a snapshot volume in on the basis of the transferred data, and transfers response information on the reconstructed data to the client.
PTL 4 describes how to prevent deterioration in performance of a system due to storing of many snapshots. Snapshots are managed in such a manner that differential data is saved to a differential volume in response to writing of data into a first storage volume. A management table for snapshots is created in such a manner that the management table is divided for each snapshot on the basis of creation time of the snapshot. The second and following management tables each store therein specified inheritance information to inherit the content of the preceding management table.